Battery Charging Question

[gciccol]

I have a 1970 16' Starcraft with a Mercury 65hp motor.

Trying to be safe when charging the battery while it's in the boat. Usually I pull the batteries out and charge them in the garage but I'm getting old and they're getting heavy.

Is it OK to leave the battery connected to the boats cables and hook up my charger to charge the battery?

Also, even when my battery is fully charged, it's about a year old, it seem to die pretty quickly when starting the engine. Sometimes I have to crank the engine quite a bit before it starts, usually when it's been sitting a while. Just wondering if these engines draw a lot of juice when trying to start.

Thanks for the help.

 

[Bobomatic]

Re: Battery Charging Question

I never disconnect my batteries. However I have a pretty simple setup - one 12v battery for main starting and the trolling motor, the other 12v battery for running lights and fish locator. For charging, I figure that as long as there is nothing running...That is, nothing is making a connection with the positive post of the batteries, the batteries are in effect 'disconnected', with nothing but some harmless wire between the battery and the various on-off switches. I could be wrong, but have not had anything too nasty happen in my several years of doing this.

Batteries going bad....It happens. I had one not too long ago only last a year or two (maybe because of the way I charge them ). Boating is tough on batteries. Like anything else, you get what you pay for. In any event, cranking on a battery will suck the juice pretty quick. Not much different than a car. My old Chevy wagon could kill a battery in a hurry.

 

[Bobomatic]

Re: Battery Charging Question

You could compromise by leaving the batteries in the boat, but disconnecting the leads (or at least the positive lead) before charging. This would eliminate the heavy lifting and any anxiety you have about leaving the batteries connected while charging. As long as anything flammable (e.g. gas tank) is not too close to where a slight spark might be generated when you make the charger connection to the battery, you should be okay.

 

[j_martin]

Re: Battery Charging Question

A couple of things about boating are generally hard on batteries. Most outboards, except the latest ones, are not voltage regulated, so they constantly overcharge the battery. Because of other factors, as long as the electrolyte is maintained, (water added) is doesn't significantly shorten the life of the batteries.

The other factor is mechanical abuse. Batteries lose a little goodie every time they're slapped around, especially if not fully charged.

So, if you get a couple of years out of a boat battery, you're doing pretty good.

The best way to extend the life of boat batteries is to get a good battery maintainer type charger, usually a couple of amps, and regulated so they shut off at 13.8 volts, and turn on when the battery voltage settles down to 13.1 or so. Put one in the boat for each battery, wire them up permanently, and plug them in when the boat is sitting.

On my bass boat, I have a 20 amp dual bank charger for the deep cycle trolling motor batteries, which are usually quite deeply discharged by the end of the day, and an 1.5 amp maintainer for the motor battery. They are all wired up so I just pull out one pigtail and plug it in when I put the boat in the garage. Water gets checked a couple of times a year, and the batteries stay in the boat all the time, even through the long winter night.

On the motor starting issue. It's very hard on both batteries and starter motors to crank more than about 10 seconds. Get it tuned up so it starts promptly.

 

[Barnacle_Bill]

Re: Battery Charging Question

Have your battery load tested and check the motor's charging circuit.

 

[Chris1956]

Re: Battery Charging Question

The battery on my speedboat must be strapped down, with several straps to keep it stationary. To charge it I would remove the motor cowling and connect the charger to the starter solenoid and ground. It was much easier.

 

[gciccol]

Re: Battery Charging Question

Thanks everyone for the solid feedback. It turns out the battery had drained down to about 50% when the engine would just crank and not start. I charged the battery to 100% and the engine fired right away.

So, I guess what I learned from this is the battery has to be almost fully charged to get the engine to actually start vs. just keep turning over.

One last question: Does anyone know if my 1970 Mercury 65hp engine does try to charge the battery as it's running? I read that somewhere but don't think my year engine is equipped to charge the battery.

 

[Skiwi]

Re: Battery Charging Question

Have a peek under the flywheel, if you can see some copper looking coils mounted up there, then yes

 

[j_martin]

Re: Battery Charging Question

Any motor that is electric start will have a charging system on it.

Connect a volt meter to the battery and notice the reading. Should be over 12.5 volts if it's near fully charged. Then start the engine and run it. The voltmeter should go up over 13V at idle, and 14 or more at higher speed. That would be charging the battery. If the battery voltage stays around 12.5, then it isn't charging.

At that point we can help you dog the problem and replace the right part.